Page 290 - Algae Anatomy, Biochemistry, and Biotechnology

Algae and Men 273

FIGURE 7.13 Frond of Macrocystis pyrifera.

Japan produces about 1500–2500 tons of alginates from kelps. China, a relatively recent addition to
the alginate manufacturers of the world, produces about 8000–10000 tons of alginates from culti-
vated L. japonica. Alginate production is valued at U.S. $213 million annually.

Carrageenan

Carrageenan is a general name for polysaccharides extracted from certain kinds of algae which are
built up, in contrast to agar, from D-galactopyranose units only. The word carrageenan is derived
from the colloquial Irish name for this macroalgae, carrageen (from the Irish place name, probably
Carrigeen Head in Co. Donegal, Carraigı ´n; “little rock”); the use of this macroalgae to extract a gel
is known in Ireland since 1810. Chondrus crispus used to be the sole source of carrageenan, but
species of Eucheuma, Ahnfeltia, and Gigartina are now commonly used. About 28,000 tons of car-
rageenan are manufactured worldwide, and although Chondrus is no longer the unique source, it is
still the principal one. Modern carrageenan is a branded product designed by mixing various types
of carrageenan, to give a gel with particular qualities. Most of the Chondrus that is used in the car-
rageenan industry comes from the Maritime Provinces of Canada (Nova Scotia, etc.), where about
50,000 wet tons of Chondrus crispus are harvested each year from natural populations. The bulk of
the harvest is collected using long-handled rakes and dredges from small boats. The macroalgae is